1. Field of the Invention
This invention relates to an ultrasonic device for measuring the acceleration of a moving reflective member, more specifically to an ultrasonic device for measuring the acceleration of a moving reflective member which detects the acceleration of a reflective member moving within a living organism and measures and displays the detected acceleration.
2. Description of the Prior Art
There are known Doppler devices which transmit a pulse wave of a given fixed pulse-recurrence frequency into a living organism and on the basis of the reflected wave received from a moving reflective member in the living organism, measure the velocity of the moving reflective member. Such devices are used, for example, in ultrasonic diagnostic devices for measuring the flow of blood or the like within the living organism. (See, for example, U.S. Pat. No. 4,573,477.)
However, the flowing blood or other moving reflective member often may not always move at a fixed velocity but may accelerate. Moreover, the acceleration of a flowing fluid such as blood is closely related to the pressure gradient acting thereon, and is thus a valuable source of data for determining pressure difference. Specifically, the acceleration of blood flow within a living organism constitutes useful information indicative of heart function and the like.
Generally, the acceleration of a moving reflective member (when the reflective member is a fluid, the local acceleration) is determined by differentiating the velocity of the moving reflective member, and to ascertain the acceleration with the required degree of accuracy, the average of the results of a large number of measurements is obtained. That is to say, the velocity is determined by an integrating operation. Therefore, where the acceleration is obtained from the velocity by a differentiating operation, the effect of the integrating operation is cancelled out, making it difficult to measure the acceleration with high accuracy.